Within a turbofan engine that utilizes a cascade type thrust reverser, there are typically a plurality of blocker doors that deploy to redirect engine bypass air thru a set of cascades that turn the airflow out and forward in order to reverse the direction of the thrust of the engine. This is done to slow an aircraft after landing. Referring to FIG. 1A, a thrust reverser system 100 is shown. The system 100 includes a sleeve 102 that is translated or moved in, e.g., an aft direction in order to expose cascades 104 as part of the deployment of the thrust reverser. Similarly, in order to place the thrust reverser in a stowed state (e.g., during flight) the sleeve 102 is translated, e.g., moved in a forward (FWD) direction, such that the sleeve 102 may contact or abut a thrust reverser fixed structure 106. When in the stowed state, the cascades 104 are not exposed. FIG. 1C illustrates the system 100 in the stowed state. An entirety of a nacelle is shown in FIG. 1C, whereas a portion (e.g., a half) of the nacelle is shown in FIG. 1A.
The blocker doors described above are typically pivotally attached to the sleeve 102 within the thrust reverser. FIG. 1B illustrates a cross-section of the system 100 of FIG. 1A about the line A-A, wherein a blocker door 108 of the system 100 is hinged to the sleeve 102 near a point 110. Additionally, the door 108 is attached to the inner fixed structure 114 of the thrust reverser via a drag link 112 that retains the door 108 in position during normal flight as well as aids in the deployment of the door 108 during thrust reverse mode.
The drag link 112 lies within the flow of bypass air from the engine's fan and generates drag losses, resulting in degraded efficiencies. Any steps and gaps around the door 108 create aerodynamic disturbances that reduce efficiency.
Additionally, the space between the point 110 and an aft cascade ring 116 may define the region where the cascades 104 are located. The dimension or length of this space is typically fixed and is selected to accommodate approximately the same airflow through the nacelle when the thrust reverser is operated in the stowed state/mode or the thrust reverse state/mode. This dimension/length contributes to inefficiencies or drag.